1. Field of the Invention
The present invention relates to an optical path control apparatus with a mirror section and a manufacturing method for the same.
2. Description of the Related Art
With the request of the communication of a large amount of data, it has been studied to apply a large capacity of optical communication to real time parallel transmission between computers, switching apparatuses, and large-scaled computers or to a subscriber system in the advanced data service. Also, the further spreading of the optical communication is demanded.
An optical module is used in the optical communication is composed of optical elements such as an optical fiber, a laser diode device (LD), a light-emitting diode (LED), and a photodiode (PD). The application fields of the optical module are being widened as the result of the high performance and high functioning of the passive and active elements of the optical module. For the optical communication to the subscriber system, it is demanded to reduce the prices of each optical element and optical module using the optical elements.
For the low price of the optical circuit, a planar type optical circuit is desirable in which the optical elements are arranged on a substrate, compared with a coaxial type module structure in which the optical elements are arranged in a block. FIG. 1 shows a first conventional example of a planar type optical module for bidirectional communication. A laser diode (LD) 102, a photodiode (PD) 103, an optical waveguide 104, a wavelength filter 105, and an optical fiber 106 are arranged on a Si substrate 101. Output light outputted from the laser diode 102 as a transmission source and having the wavelength of 1.3 xcexcm is inputted to the optical waveguide 104, and is outputted from the optical fiber 106 via the wavelength filter 105. An optical signal transmitted through the optical fiber 106 and having the wavelength of 1.55 xcexcm is inputted to the optical waveguide 104, an optical path of the optical signal is changed into an adjacent waveguide by the wavelength filter 105, and then the optical signal is inputted to the photodiode (PD) 103 for reception of the optical signal. In this way, using the planar type light circuit, a small optical transmission and reception module can be realized. In a conventional semiconductor process, grooves are formed for positioning the optical waveguide 104, the wavelength filter 105, and the optical fiber 106 on the Si substrate 101. With this, it is possible to reduce the manufacturing cost, and the installation cost and the decrease of the installation area is realized.
Optical devices are divided into a first type of optical devices such as the light-emitting diode (LED) and the photodiode (PD) and a second type of optical devices such as the laser diode (LD). When the optical device is installed, the light is emitted or received from and by the surface of the optical device in the first type of optical device, while light is emitted from or received by the side surface. When the two types of devices in which light axes are orthogonal to each other should be arranged on the substrate and optically coupled to each other, the optical path conversion of 90 degrees is needed.
As shown in a second conventional example of FIG. 2 by Masataka Itoh, et. al., (46th Electronic Component and Tecnology Conference, p. 1), an output light from an optical fiber 106 is reflected by a sloped reflection plane 109 which is produced by anisotropically etching a silicon substrate 101. Thus, an optical path is changed into the direction to the photodiode (PD) 103. However, in this method, the substrate material is limited to silicon and a substrate of other material cannot be handled.
Also, as shown in a third conventional example of FIG. 3 disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 7-159658), a prism is known as an optical path conversion element. The optical path of a light beam 107 outputted from an optical waveguide 104 is changed by 90 degrees by a prism 108 or a reflection surface 109 of a reflection mirror. The manufacturing cost of the prism smaller than 1-mm size is high and the use of such a smaller prism causes the increase of the number of parts and takes a long installation time.
A fourth conventional example in which an optical path is not changed is shown in FIG. 4. For the installation of a photodiode (PD) 103 in a non-planar state, a three-dimensional position adjusting tool is newly necessary. For example, it is necessary to add another substrate 110 to support the photodiode (PD) 103 and parts to fix the substrate on an adjustment position, resulting in more increase of the manufacture cost.
By the way, light outputted from light-emitting device such as a light-emitting diode or a laser diode has a radiation angle. Therefore, even if a waveguide or an optical fiber is arranged in the neighborhood of the radiation section of the light-emitting device, a light loss is large. However, it is difficult to produce a lens with a good light convergence for a small light loss, resulting in more increase of the manufacturing cost.
Even if the above problems are supposed to have been solved, a light switch as an optical path control apparatus becomes necessary for the optical path conversion. As the optical path control apparatus, an un-movable switch and a movable switch are known. The technique using the electro-optic effect and magneto-optics effect of optical crystal is known in the un-movable switch. As the movable switch, the technique to drive an optical fiber mechanically is known as shown by R. Jebens et. al., (Sensors and Actuators 20, pp. 65-73, 1989), or the technique to drive a small mirror (Micro-opto-electro-mechanical-systems: MOEMS) is known as shown by L. Y. Lin. et. al., (IEEE Photon Technol. Lett. 10, 1425, 1998) and by J. Mohr et. al., (Technical Digest of International Conf. on Optical MOEMS and Their Applications, p221-226). The latter technique is expected as the technique for realizing a large-scale light switch cheaply.
The above-mentioned light switch of MOEMS is produced by applying a semiconductor fine fabrication technique to a silicon substrate. According to the above technique, there is a problem that the substrate material is limited to silicon, and the light switch cannot be realized on a printed circuit board whose inside layer wiring is possible. An example in which a mirror and an electrostatic actuator are formed by a Ni plating method in LIGA (Lithographie Galvanoforming Abforming) process is known. However, there is a problem in that the surface roughness of the mirror is large and the light loss is large.
An optical path adjustment between the optical fiber and the photodiode (PD) in the optical module is mainly carried out using the flat surface of the silicon substrate as shown in above-mentioned technique (Masataka Itoh, et. al.). However, because a substrate other than the silicon substrate cannot be used as the substrate for the optical module, the flexibility of manufacturing the optical module is restricted strongly.
In conjunction with the above description, an optical waveguidexe2x80x94optical device coupling structure is disclosed in Japanese Laid Open Patent application (JP-A-Heisei 7-159658). In this reference, an optical waveguide and an optical device are optically coupled which are formed by laminating different dielectric layers on a dielectric substrate. The dielectric substrate has a groove section provided in front of an end of the optical waveguide on the installation side of the optical device, to have a base surface parallel to the optical waveguide surface. A prism is installed on a position where the light axis of the optical waveguide and the light axis of the optical device are coincident with each other. The optical device is installed onto the dielectric substrate over the prism and the optical waveguide.
Also, a manufacturing method of a micro mirror is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 9-218304). In this reference, a reflection film is formed on a flat surface of a substrate. The substrate is cut away from the other surface of the substrate to the reflection film using a dicing blade which has the tip angle of 90 degrees. The substrate is cut to keep a predetermined width of the reflection film and to have a cut plane orthogonal to the above cut plane. Thus, the micro mirror is produced.
Also, a light switch is disclosed in Japanese Laid Open Patent Application (JP-P2000-121967A). In this reference, a counter bore is formed in a substrate. A movable plate is formed in the counter bore to be coupled to the substrate via a pair of flexure sections. A mirror is formed on the upper surface of the movable plate. The mirror is formed to have a right angle to the movable plate and to have an inclined surface to input light.
Also, a light switch is disclosed in Japanese Laid Open Patent Application (JP-P2000-258704A). In this reference, a movable electrode 12 is provided in parallel to the surface of a conductive substrate and movably in a direction perpendicular to the substrate surface. A micro mirror is installed on the movable electrode 12. A concave section is formed in a surface portion of the substrate by an etching process. The bottom surface of the concave section functions as a fixed electrode surface to the movable electrode.
Also, a micro actuator is disclosed in Japanese Patent No. 3,076,465. In this reference, a driving section has a fixed electrode and a movable electrode. Each of at least two driven sections is supported by a joint at one end. The driven section is repeatedly bent at the joint. The driving section drives the driven section by electrostatic force generated when a voltage is applied between the fixed electrode and the movable electrode. The displacement direction of the driven section is different from the direction of the force generated by the driving section.
Therefore, an object of the present invention is to provide an optical path control apparatus with a mirror section in which the mirror section is installed three-dimensionally.
Another object of the present invention is to provide an optical path control apparatus with a mirror section in which various types of substrates can be used.
Still another object of the present invention is to provide an optical path control apparatus with a mirror section in which the mirror section can be driven simply.
In an aspect of the present invention, an optical path control apparatus includes a first substrate; a second substrate movably provided for the first substrate; a mirror section provided on the second substrate; and a driving section which moves the second substrate such that a first optical path of input light to the mirror section is optically connected to one of a plurality of second optical paths.
Here, the driving section may be a ultrasonic wave generating source, and the second substrate may be moved by progressive waves generated by the ultrasonic wave generating source and may be located on a position by standing waves. Thus, the first optical path is optically connected to the second optical path associated with the position.
Also, the driving section may be an ultrasonic wave-generating source is a piezo-electric device.
Also, the driving section may include two electromagnets, and the second substrate may be a permanent magnet provided between the two electromagnets. The permanent magnet is moved between two positions based on magnetic polarities of the two electromagnets, and the first optical path is optically connected to the second optical path associated with one of the positions.
Also, the second substrate has a gear shape, and the mirror section is provided on the second substrate via a base section. The driving section may have an electrostatic actuator, and rotate the second substrate based on force generated by the electrostatic actuator such that the mirror section is rotated. The first optical path is optically connected to the second optical path associated with a rotation angle of the mirror section.
Also, the second substrate has a micro light wheel. The driving section may have lasers, and rotate the second substrate based on laser beams emitted by the lasers. The first optical path is optically connected to the second optical path associated with a rotation angle of the mirror section.
Also, the second substrate may be provided in a concave section of the first substrate, and the concave section may be filled with fluid. The driving section may move the second substrate by supplying the fluid from one end of the concave section and absorbing the fluid from another end of the concave section. The mirror section reflects the input light based on the movement of the second substrate such that the first optical path is optically connected to the second optical path.
Also, the mirror section may be a thin film mirror or a lump type mirror.
In another aspect of the present invention, an optical path control apparatus includes a substrate; and a mirror section which is provided on the substrate and changes an optical path of reflection light to input light by the mirror section in response to an input signal.
Here, the mirror section having two mirror portions, each of which may include: a mirror layer provided as a surface layer; and an underside layer provided under the mirror layer and having a conductive line. The tow mirror portions attract or repel each other based on current as the input signal supplied to the conductive lines such that a reflection angle of the mirror section is changed.
Also, the mirror section may include: a mirror layer provided as a surface layer; a transformed layer provided under the mirror layer; and an electrode layer provided under the transformed layer. The mirror layer of the mirror section is transformed through transformation of the transformed layer in response to supply of the input signal such that a reflection angle of the mirror section is changed.
Also, the mirror section having two mirror portions, each of which may include: a mirror layer provided as a surface layer; and a magnetic layer provided under the mirror layer. The tow mirror portions attract or repel each other through magnetization of the magnetic layer based on the input signal such that a reflection angle of the mirror section is changed.
Also, the mirror section may include: a mirror layer provided as a surface layer; a shape memory layer provided under the mirror layer; and a heating layer provided under the shape memory layer. The mirror layer of the mirror section is transformed due to transformation of the shape memory layer through heating by the heating layer in response to the input signal such that a reflection angle of the mirror section is changed.
Also, the mirror section may be a thin film mirror, or the mirror section is a lump type mirror.
In Still another aspect of the present invention, a method of manufacturing a mirror section is achieved by providing a die of semiconductor having a concave section; by forming a copper layer on a surface of the die; by forming a mirror film on the copper layer; by forming a transforming film on the mirror film; by film to produce a laminate structure of the copper layer, the mirror film, and the transforming film; by transferring the laminate structure onto a base; and by removing the copper layer to produce the mirror section on the base.
Here, the step of forming the transforming film may include the steps of: forming a transformed film on the mirror film; and forming an electrode film on the transformed film. In this case, the transformed film may be formed of one of electric-distortion material, magnetic distortion material, and opto-magnetic distortion material.
Also, the method may further include the steps of: forming a resist layer on the mirror section; forming an opening in the resist layer corresponding to a tip portion of the mirror section; and removing the tip portion of the mirror section.
Also, in another aspect of the present invention, a method of manufacturing a mirror section is achieved by forming a connection layer on a base; by locating a bump on the connection layer; and by pushing a die against the bump to produce a mirror section.
Also, in another aspect of the present invention, an optical path control apparatus includes a first substrate; a second substrate movably provided for the first substrate; a mirror section provided over the first and second substrate; and a driving section which moves the second substrate such that a first optical path of input light to the mirror section is optically connected to one of a plurality of second optical paths.
Also, in another aspect of the present invention, an optical path control apparatus includes: a thermal transforming cell; a mirror section provided on the thermal transforming cell; and heating section which heats the thermal transforming cell.
Also, in another aspect of the present invention, a method of switching an output optical path is achieved by reflecting input light on an input optical path onto a first output optical path by a mirror section; by moving or transforming the mirror section; and by optically connecting the input light to a second output optical path through the movement or transformation of the mirror section.
In this case, the step of moving or transforming the mirror section may be achieved by one of electrostatic force, magnetic force, force generated by ultrasonic waves, optical force generated by laser beam, pressure of fluid, and mechanical force.